About this article
This article was created using an automated generation workflow powered by generative AI. Based on the official curl documentation, we outline how to analyze communication times by breaking them down into DNS, connection, and time to first byte.
Verification Status: 📘 Verified with official curl specifications, actual communication not verified
When a web page is slow, looking at each phase separately rather than just the total time makes troubleshooting much easier.
Try this first
curl -o /dev/null -sS -w 'dns=%{time_namelookup}nconnect=%{time_connect}nfirst_byte=%{time_starttransfer}ntotal=%{time_total}n' https://example.com/
Check here
dns、connect、first_byte、total View the values in this order. Since the values are cumulative, do not add the four values together.
Change one thing
Change only the URL to another public site and compare which values change significantly. Do not judge performance based on a single measurement.
Why?
Name resolution, TCP connection, and server response initiation are distinct phases. Breaking down the total time helps narrow down where to check next.
For professional use
You can convert users' complaints of slowness into concrete numbers during initial troubleshooting of internal web applications and APIs. Please execute according to your target system's operational policies.
